The present invention relates to technique of controlling a continuously-variable transmission, and more specifically to a shift control based on input and output disk speeds, or to a shift control for a toroidal continuously-variable transmission having a shift hydraulic actuator used for both a forward vehicle traveling operation and a reverse vehicle traveling operation.
A Published Japanese Patent Application Kokai No. H09(1997)-250618 shows a toroidal continuous-variable transmission (TCVT) having two different shift control hydraulic system for forward and reverse operations. A U.S. Pat. No. 6,226,583 B1 (corresponding to a Published Japanese Patent Application Kokai No. H11(1999)-91413) treats a problem of torque shift in a toroidal continuously-variable transmission.